Integrated circuit (IC) chips are typically enclosed in packages to provide environmental and mechanical protection as well as electrical connection with a circuit board or other components. Such packages have generally included a body of nonconductive material with external lead pins by which the chip encased therein can be connected to a circuit board.
A substantial portion of the cost and size of a packaged chip is attributable to its package, and two important design criteria in addition to providing a reliable electrical connection are cost effectiveness and space efficiency. Further, it is generally desirable to design such packages for quick and easy disconnection to facilitate testing and replacement.
It will be appreciated that many electronic applications require functional cooperation between two or more IC chips. For example, microprocessor chips with the desired program logic contained therein are often utilized in conjunction with erasable programmable read only memory (EPROM) chips containing stored parameters which can be erased by ultraviolet light and reprogrammed with new parameters as necessary. A window must be provided in the package of the EPROM chip for transmission of the ultraviolet light. It is of course possible to combine the functions of a microprocessor and EPROM into a single monolithic integrated circuit and package, however, this has proven to be quite expensive due to the low chip per wafer yield associated with the manufacture of semiconductor devices and the relatively low production rates of such monolithic chips.
Although integrated circuit packages are not usually adapted for such, recently there have been efforts to adapt such packages for stacking to achieve greater circuit board density and space efficiency. For example, my copending application Ser. No. 053,879 discloses and claims an integrated semiconductor package capable of supporting separately packaged semiconductors. The supporting or base chip is interconnected electrically to lead pins and socket contacts by means of conductive circuitry compatible with other semiconductor packages. Even these packages, however, have tended to be expensive due to the additional components and manufacturing steps involved in their fabrication.
A need thus exists for an improved semiconductor package having pin and socket connections integrally formed therein for plug-in compatability with circuit boards and other semiconductors.